A double multi-vane type rotary fluid machine system is described in Japanese Patent Application Laid-open No. 59-41602. In this rotary fluid machine system, a circular vane-supporting ring is disposed between an elliptic outer cam ring and an elliptic inner cam ring, and outer and inner ends of a plurality of vanes radially slidably supported on the vane-supporting ring are in abutment against an inner peripheral surface of the outer cam ring and an outer peripheral surface of the inner cam ring, respectively. Therefore, when the vane-supporting ring is rotated relative to the outer cam ring and the inner cam ring, the volumes of a plurality of vane chambers partitioned by the vanes between the outer cam ring and the vane-supporting ring are increased or decreased and in this manner, the rotary fluid machine system functions as an expander or compressor. In addition, the volumes of a plurality of vane chambers partitioned by the vanes between the inner cam ring and the vane-supporting ring are increased or decreased and in this manner, the rotary fluid machine system functions as an expander or compressor.
In this double multi-vane type rotary fluid machine system, the outer and inner rotary fluid machines can be used as independent expanders, respectively; the outer and inner rotary fluid machines can be used as independent compressors, respectively; and one and the other of the outer and inner rotary fluid machines can be used as an expander and a compressor, respectively.
A vane-type rotary fluid machine system capable of being used as an expander or a compressor is described in Japanese Patent Application Laid-open No. 60-206990. In this rotary fluid machine system, a circular intermediate cylinder is disposed eccentrically between a circular outer cam ring and a circular inner cam ring disposed concentrically with each other, and outer and inner ends of a plurality of vanes radially slidably supported in the intermediate cylinder are in abutment against an inner peripheral surface of the outer cam ring and an outer peripheral surface of the inner cam ring, respectively. Therefore, when the intermediate cylinder is rotated relative to the outer cam ring and the inner cam ring, the volumes of a plurality of vane chambers partitioned by the vanes between the outer cam ring and the intermediate cylinder are increased or decreased and in this manner, the rotary fluid machine system functions as an expander or a compressor. In addition, the volumes of a plurality of vane chambers partitioned by the vanes between the inner cam ring and the intermediate cylinder are increased or decreased and in this manner, the rotary fluid machine system functions as an expander or a compressor.
In this vane-type rotary fluid machine system, the outer and inner rotary fluid machines can be used as independent expanders, respectively; the outer and inner rotary fluid machines can be used as independent compressors, respectively; and in addition, the outer and inner rotary fluid machines can be connected in line to each other and operated as a two-stage expander or a two-stage compressor by allowing a working fluid passed through one of the outer and inner rotary fluid machines to be passed through the other rotary fluid machine.
A rotary fluid machine disclosed in Japanese Patent Application Laid-open No. 2000-320543 includes vane piston units each including a combination of a vane and a piston, so that the pistons slidably received in cylinders mounted radially in a rotor convert a pressure energy of a gas-phase working medium and a rotational energy of a rotor from one into another through a power-converting device including an annular groove and a roller, and vanes radially slidably supported in the rotor convert the pressure energy of the gas-phase working medium and the rotational energy of the rotor from one into another.
In such a vane-type fluid machine, the volume of a vane chamber defined between a pair of the adjacent vanes is decreased in an exhaust stroke and increased in a suction stroke, but in order to prevent the blowing-through of the working medium between an exhaust port and an intake port, it is desirable to eliminate a period during which the vane chamber is simultaneously in communication with the exhaust port and the intake port. In this case, if the volume of the vane chamber is decreased or increased for a period from the end of the exhaust stroke at which the vane chamber and the exhaust port are put out of communication with each other to the start of the suction stroke at which the vane chamber and the intake port are put into communication with each other, the following disadvantages occur:
When the volume of the vane chamber is changed during such a period, if the lubricating water or oil which is a non-compressible fluid is confined in the vane chamber, there is a possibility that a so-called water hammer phenomenon may be generated to cause a vibration or a noise, or a larger load may be applied, resulting in a reduction in durability. In the expander, as soon as the intake port which is a high-pressure port is put into communication with the vane chamber, if the amount of protrusion of one of the pair of vanes defining the vane chamber, which is located on the side of the exhaust port, is large, there is a possibility that the pressure of the high-pressure working medium drawn from the intake port to the vane on the side of the exhaust port may be applied, whereby the rotor may be rotated reversely, or a torque for rotating the rotor reversely may be generated.
At the cold starting or the like of the rotary fluid machine including the pistons, the gas-phase working medium supplied to cylinders may be cooled and liquefied in some cases. If each of the pistons is moved in each of the cylinders in this state for a period from the closing of a gas-phase working medium discharge port of a rotary valve for supplying and discharging the gas-phase working medium to and from the cylinder to the opening of a gas-phase working medium supply port, there is a possibility that a so-called water hammer phenomenon is generated to cause a vibration or a noise, because a liquid-phase working medium confined in the cylinder is a non-compressible fluid.